Multiscale Fracturing in Medium- to Low-Rank Coals and Its Implications on Coalbed Methane Production in the Baode Area, Eastern Ordos Basin, China

Table 4

Helium permeability test results of the samples.

Samples	Fractures	Confining pressure (MPa)	Inlet pressure (MPa)	Outlet pressure MPa)	Flow rate (cm^3/s)	Permeability (10^−3 μm^2)
1	Developed	7.0	1.5	1.0	3.58	40.78
		9.0	1.5	1.0	3.17	36.04
		11.0	1.5	1.0	2.92	33.19
		13.0	1.5	1.0	2.58	29.40
		15.0	1.5	1.0	2.42	27.50
		17.0	1.5	1.0	2.08	23.71
2	Developed	7.0	2.0	1.0	6.67	31.61
		9.0	2.0	1.0	5.33	25.29
		11.0	2.0	1.0	5.00	23.71
		13.0	2.0	1.0	4.33	20.55
		15.0	2.0	1.0	3.83	18.18
		17.0	2.0	1.0	3.50	16.60
3	Developed	7.0	1.5	1.0	1.00	8.88
		9.0	1.5	1.0	0.92	8.14
		11.0	1.5	1.0	0.72	6.37
		13.0	1.5	1.0	0.58	5.18
		15.0	1.5	1.0	0.33	2.96
		17.0	1.5	1.0	0.29	2.59
4	Developed	7.0	2.0	1.0	2.25	8.33
		9.0	2.0	1.0	2.12	7.83
		11.0	2.0	1.0	1.92	7.09
		13.0	2.0	1.0	1.45	5.37
		15.0	2.0	1.0	1.17	4.32
		17.0	2.0	1.0	1.08	4.01